Containers of this type, which can be configured as, for example, injectors, have long been known. In EP-A1-0 063 891, one approach to configuring such a container includes an application tip with a closure cap, whereby pasty material is provided in the application tip. A plunger ram pushes an injection plunger into an injector housing, whereby the corresponding geometrical configuration of the injector plunger is chosen such that only the smallest possible remaining amount of material remains in the injector housing following the application of the material.
In accordance with the above-noted patent application, a closure cap is provided which is color-coded. The application of the color-coding ensures that the application tip and the closure cap are recognized as being elements associated with one another, such that an inadvertent placement of a closure cap on the incorrect application tip is avoided.
The background relating to the use of such containers is that different masses or substances can be applied with correspondingly colored, differently configured application tips. The different pasty masses comprise, in their applications in the dental practice, special properties which can be adversely impacted by contamination. It is, however, important that the dentist or the dental technician can rely upon the fact that the property of the applied mass or substance is, in fact, as promised.
The applied mass is typically, on the other hand, a photo polymerizable mass. The customary storage of such masses in a closed and light impermeable cabinet permits the use of masses which have been maintained in a relatively long storage state without quality degradation. If, on the other hand, the identification of a mass is to be undertaken based upon the application tip which applies the mass, which has been removed, it is important that the application tips also are stored in the normal course of use in a light impermeable cabinet in view of the fact, for example, that a yellow application body exhibits a considerably larger light transmission capability than a dark blue injector housing. For this reason, in accordance with the above-noted patent application, a substantially thick walled housing is provided.
It is, indeed, possible to choose a two-layer configuration for the injector housing and to produce the inner layer from a light blocking material. This approach is, however, clearly more expensive and requires a higher production precision for conforming the layer thicknesses to one another, for securing the layers to one another, and for assuring the sealing integrity.
A disadvantage of the heretofore deployed systems lies in the fact that the injector components must be manufactured together with the application tip. To be sure, the injector components can be manufactured as throw away or disposable articles which are still, basically, substantially cost favorable. However, there exists the problem that the viscosities of the masses to be applied vary. In this connection, it would be desirable to provide a suitable flow resistance in the application tip which is selected as a function of the viscosity of the mass to be applied. The dentist or dental technician should be able, to the extent possible, to apply the same actuation force independent of the viscosity of the mass to be applied, thus leading to an ergonomically optimized operation and permitting a delicately sensitive dosing.
In connection with known or conventional injector components, a trade-off has been accepted that the actuation force will vary in correspondence with the properties of the mass to be applied, as otherwise the production of numerous different injector components with diameters selected as a function of the viscosity of the masses would be too labor intensive. In addition, it must also be taken into account that the viscosity of newly developed masses varies. In this regard, typically a compromise has been struck with respect to configuring the flow resistance during the application of the mass in that it has been decided to configure the injector to have an average flow resistance to the mass to be applied.
On the other hand, the demand for applied dental masses is increasing so that it can be expected that, in the future, the number of masses to be applied having differing viscosities will increase still further.